Rotary waveguide joint and switching structure



L. D. STROM 2,945,193

AND SWITCHING STRUCTURE Jul 12, 1960 ROTARY WAVEGUIDE JOINT 5Sheets-Sheet 1 Filed. Feb. 2. 1954 INVENTOR.

- lzL/i/voflSmo/vr x 46 mzwwww ATTORNEYS July 12, 1960 1.. n. STROMROTARY WAVEGUIDE JOINT AND SWITCHING STRUCTURE Filed Feb. 2. 1954 5Sheets-Sheet 2 W7 W8 a 0 W. k

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Arro/e/vgvs L. D. STROM 2,945,193

ROTARY WAVEGUIDE JOINT AND SWITCHING STRUCTURE July 12, 1960 5Sheets-Sheet 3 Filed Feb. 2. 1954 INVENTOR. LELfl/Vfl D. STROM ATTORNEYS L. D, STROM 2,945,193

ROTARY WAVEGUIDE JOINT AND SWITCHING STRUCTURE July 12, 1960 5Sheets-Sheet 4 Filed Feb. 2. 1954 INVENTOR. LEAH/v0 Q STROM ATTOEMFYS1.. D. STROM 2,945,193

ROTARY WAVEGUIDE JOINT AND SWITCHING STRUCTURE July 12, 1960 5Sheets-Sheet 5 Filed Feb. 2. 1954 INVEN TOR. ZnA/vo J'TAOM A TTOE/VE vstes ROTARY WAVEGUIDE worm AND SWITCHING STRUCTURE T Leland D; Strom,Dallas, Dallas County, Tex., assignor to Texas Instruments Incorporated,Dallas, Tex, acorporation'of Delaware Filed'Feb: 2, 1954, Ser. No,407,635

17 Claims. (Cl. '333-.-7)

This. invention relates to. a rotary jointand switching structure. andmorev specifically, to. a rotary joint, of. the

rectangular waveguide. type so constructed as to transfer R.-F..power.t0 an antennarotatingthrough360 degrees, or to switch R.-F. poweralternately to morelthanone antenna vfeed while maintaining. 3.60degreesrotation-of the antenna :array...

It will be appreciated that rotary waveguide joints .as such .are notnew- Prior art joints have beendeveloped using the circularTM modeandithe rectangularuTE mode. One of thislatter type of joints wasadisclosed in a NavalResearch Laboratory Report in 1951 by Breetz andembodied in Patent.No. 2,595,.l-.86 issued April 29, 1952,10: Breet zQTherotary joint in the referred to. report consists :of a. rectangularwaveguide sbent in the -E-plane :to form a complete circler with thewaveguidesplit along the narrow wall to permit relative motionflbetweenthe respective: sections. Waveguides-iconnected into the opposite andfacing wide sides of the waveguide sections form 'the power input-andoutput for the joint with the input guideconnected to the inner sectionand. the output guideqto the outer section. At the junction points ofthe input and output guides to their respective sections of the circularguide are sets of fingers. extending into the guide and directed at suchan angle as to make E-plane bends for the feed to and from the rotaryjoint. The fingersinzthe E-plane bend are set at approximatelya 45degreerangle with .the tangentto the circumference of the circlewhere-the fingers enter the ring and serve to'jdirect the pathpf thewave fr-om the input guide through the rotary joint and-to the outputguide. These fingers attaehedto the relativelyrotating Sections arearranged to interleave thus permitting 360-degree rotation.'- p

Although it is'essential to direct the path. of the input wa e yet itis-undesirable for several reasonsrtor direct the wave pathwby usingsets of interleavingfingers. Ihfe practieal difiiculty of fixing thefingers to the input and output isect-ions because of the :relativelysmall dimensions: of the waveguide constitutes a disadvantage ofthis-apparatus. Further, :the difficulty ,in setting" the arcing takesplace causing undesirable zrefiections. into the input arm.- Thisnecessarily means'that when fingers 'areused to direct the path of thewave from 'the input guide to the output guide, therotaryjointissinherently limited to a 'low' amount ofipower that can .betransferred through the joint. 1 Accordingly it is aprincipal object ofthis invention to' provideqan apparatus' that willavoid the low power Itraiisfer limitat-ions .of previously-known rotarynwavee guide-jointsubyutilizing. devices -:.which have directional A 2,945,193 Pa en ed July969 2 characteristics of themselves without. the necessitylof usingpower limiting devices such as interleaving fingers to accomplish wavepath directivity. It is another object of this invention to provide anapparatus that willavoid construction difiiculties present with priordevices and one which will be simpler and more easily constructed.

It is a further object of this invention to provide structure .which canbe easily adapted for switching the input power between two ormoreantennas. s

It is still another object of this invention to proyide a small, compactstructure suitable for stackingonejoint upon another with colinear axesof rotation for feeding an array of antennas without interferencebetweenthe various feed arms to the antennas.

Other and further objects of the invention aswell as the characteristicsof the structure necessary to accomplish the above enumerated'objectswill become. apparent from the following discussion For thispurpose thediscussion is referenceduto the following .drawingsai n which:

Figure 1 is a partially broken-away perspectiveview of the preferredembodimentof. the invention showing a directional-coupler. as thedirectivedevicer. 1

Figure, 2 is avcross-sectionalqview.of Figure intake]; in a radial plane.passing,symmetrieallythro l h the device showing the .wave path ...asdirected by the :inputsaud output directional couplers;.. I l Figure i,is 'al view similar to Figure 2il-lustrating wave paths at thecross-over positien;..

Figure 4 is a perspectiveview partially. broken away showing. .the use.of hydridtTs as, a modification .ofthe invention;

Figure 5 is a cross-sectional view of Figure4-takenin a radial plane.passing symmetrically. through the (if/Vice illustrating the wave patharound-the rotary jointrtoarthe E-arm of the hybrid T;

Figure 6 is aperspecti-ve view of the device show-nip Figure 4 showingthe wave paths into the E andH-arngs of the hybrid T at the cross-overpoint;

Figure '7; is a partially broken-away perspective-vie w of a directionalcoupler switching arrangement according to another modification of theinvention; 1

Figure 8 is a cross-sectional view of Figure 7 takenrin a radial plane.passing symmetrically through the device;

Figure 9 is a perspective view of a hybrid' lswitching arrangementaccording to a further embodiment ;of the invention; and

Figure 10 is a cross-sectional view'of FigurerQQ-taken in a radial planepassing symmetrically nthrough the device. 7

Referring now to the various figures, it:.can:be seen that thebasiestructure, of the rotary jointis-identical for all embodiments ,ofthe present inventionuwithwthe dilferences between the severalembodiments beingsinathe means for accomplishing wave pathsdirectivity.IBasi-i cally, the rotary jointgconsists of arotor-20 and-astatoli 21.Rotor -20 is a cylindrical annulus in shape with a raised area aroundits mid-portionwhich .forrns three sides of a waveguide :24. '1 The;wide .side .of waveguide 24 is designated by the number 22-and themarrowsides by the number 23, all an integral part-of rotor 20. Theclosure of waveguide 24 is effected by the side wall of stator 21 whenthe stator is in rposition within rotor 20. Stator 21 is also acylindrical annular structure, however, it is further formed with-twoinwardly extending circular annular sections 26 and..28 located towardthe upper and lower vends .of the stator 21 respectively: slot .25 iscut into section 26 to a .depth equal to a quarter wave length attheaoperatinglfrequency' of the system and is connectedwith themainguide: 24 bymeans of-another quarter 'wave length passage 34a formedbetween the rotor and stator. Thus, slot 25 is located at a quarter wavelength above waveguide 24 and acts as a choke to prevent the loss ofR.-F.- power.

Fro'm transmission line theory, the voltage is amaxiand the current isessentially zero at a point located at. a quarter wave length from ashort circuit in a transmission line. Consequently, an impedanceapproaching infinity is possible 'at the junction of slots 25 and 34a.This high impedance is in turn transformed through a quarter wave lengthsection 34a, resulting in an effective short' circuit at the junction ofslot 34a and waveguide 24. 'It should be recognized that passage 34a isformed as a result of reducing the diameter of stator 21 to avoidmetal-to-metal contact with rotor and is as narrow as possible. In likemanner, a quarter wave length slot 27 is formed in the lower section 28and is connected by quarter wave length passage 34b with the lower sideof waveguide 24. r a

Although not shown, it is necessary for the stator and rotor sections tobe maintained in their relative positions by means of a suitable bearingarrangement. This can be accomplished by using stator 21 as the innerrace and attaching cover plates to either end of rotor 20 to serve asthe outer races of a ball bearing movement. The rotary joint is notrestricted to the above designation of rotor and stator sections becausethe construction of the joint allows either to be used as the rotating 7or; stationary section. Further, if the rotary joint is to be used in apressurized system, '0 seal rings can be provided for this purpose.Sealing means is shown in Figure 1 and consists of 0 seal ring 38 ingroove 29 and '0 seal ring 32 in groove 31, located at the upper andlower ends of stator 21 respectively.

7 In the operation of the embodiment shown in Figure 1, wave pathdirectivity is accomplished by means of directional couplers. The R.-F.power is fed from input guide 33- into a directional coupler 35, whichfits into an opening provided in the side wall of stator 21. Twomutually perpendicular slots 36 and 37 are formed into the wall ofdirectional coupler 35 facing the circular waveguide 24. These slots 36and 37 are each resonant at the operating frequency of the system and,consequently, tend to effect practically a 100 percent transfer of powerfrom the coupler into the waveguide 24. A,

high-dielectric strength plug 38 that does not materially raiuce thetransfer of power is inserted into the opening provided by the mutuallyperpendicular slots 36 and 37. It may be desirable also to insert a plugof highly absorbent material, connnonly termed lossy material in theart, into directional coupler 35 at the terminal indicated by thenumeral 48.

- A directional coupler 42 is fixed to an opening cut into the wide face22 of the circular waveguide 24 and serves as the power output from therotary joint. Directional coupler 42 has two mutually perpendicularslots 39 and 40 filled with a high dielectric strength plug 41 in thesamemanner as directional coupler 35. It can pled into the waveguide 24where it travels in the direction indicated by path 45 as the preferreddirection until it reaches the coupling slots 39 and 40 in directionalcoupler 42. Slots 39 and 40 directionally couple the wave into coupler42 where the wave takes the path indicated by numeral 46 to the outlet43 of the coupler.

It is obvious that if there is relative movement between rotor 20 andstator 21, path, 45 will change in length until the slots 36 and 37 haverotated relatively to a point directlyopposite slots 39 and 40 as shownin Fig, ure 3. This varying path length makes no difference until theslots in the two couplers are directly opposite and reach what is termedthe cross-over point. When this point is reached, the R.-F. power splitsand a portion follows path 45 around the circumference of the ring jointwhile a portion follows path 47 directly across to directional coupler42 and recombines with the wave following the path 45. In order to avoida recombinaflected waves can be minimized by a proper design of therotary joint path lengths.

.In Figure 4, the structure of the rotary joint is identical to thatshown in Figure 1 with the exception'of the input and output directionaldevices. The directional coupler at the input in Figure 1 is replaced inFigure 4 by'a miter corner 51 extending into the waveguide 24 at anangle of 45 degrees. .The effectiveness of the mitered cornermay beincreased by a folded choke (not @shown'). At the output, thedirectional coupler of Figure 1'is r'e placed by a hybrid T consistingof an E-plane arm 53 fed through opening 52 in the wide face 22 ofcircular guide 24 and H-plane arm 58 fed through opening 56 in thenarrow wall 23 of the circular waveguide 24. The hybrid T is a four-armdevice consisting of two colinear arms, which in this instance isprovided by the waveguide 24, and the E-plane and H-plane side arms 53and 58 respectively. v

The hybrid T, a well known device in the waveguide art, has the specialproperty when power is applied at one terminal of transmitting withcertain prescribed amplitude and phase relationships to a second andthird terminal but not to the fourth. Thus, in Figure 5, as R.-F. poweris applied to the input arm 33, it propagates along path 60 of the inputarm and is directed into waveguide 24 by the miter corner 51. Thisenergy travels path '61'around the circular guide until it reaches theopenings 52 and 56 into the E and H-arms of the hybrid T. The powersplits at this point and divides equally be seen that the plugs 38 and41 are important in increasing thepower transmission characteristics ofthe rotary joint since without the use of such material, breakdownacross the slot gaps would occur at a lower power rating. The output ofdirectional coupler 42 is fed to an antenna by means of a waveguide (notshown) connected to opening 43.

A directional coupler may be defined as a device which, when inserted ina transmission line with waves traveling in both directions, delivers toa pair of terminals located in an auxiliary transmission line a voltagewhich is largely a function of the amplitude of the wave going in onepreferred direction, and relatively independent of the wave going in theopposite direction. In Figure 2, the path of the wave delivered by inputguide 33 to directional coupler 35 is indicated by path 44. The.

between the arms, the power following path 62 into the E-arm while thepath of the wave into the H-arm is not shown in Figure 5. In order thatthe hybrid T may be most useful, the inputarms should have noreflections when non-reflecting terminations are placed on theasymmetrical arms. Therefore, matching elements can be provided in theE-plane and the H-plane' arms to produce reflections that cancel thereflections from the junction. These matching elements are provided byiris 54 in E-arm 53 and iris 57 in H-arm 58 as shown in Figure 4. Thearms of the T-junction will then be reflectionless when the colineararms are terminated with reflectionless loads.

From the above description of the hybrid T, it is apparent that the waveamplitude in arms 53 and 58 is half the amplitude of the original waveand it is further known from the waveguide art that the waves havecertain phase relation with each other. The phase relation between thewaves'in a hybrid varies depending upon the structure of the hybrid, butfor the hybrid T the waves in the asymmetrical arms are degreesout-of-phase when .excit'ed by one of the colinear arms. Y By. takingads/an.

gem-tea tage'is of the law ofrecipr-ocity governing hybrid Ts, the wavesin theE -and H-arms may be recombined in a second hybrid T (Figure 11)to deliver the total power of the original wave to the antenna. Thephase and amplituderelationot the rotary joint output arms arepreservedwandthe E-arrn 53v is connected to the E-arm 1 0 of' the secondhybrid T and the H-arrn 58 to the H-ai'm ltll. It is'evident that sincein the second bybrid T all particulars of the energy flow in the firsthybrid T are reversed, all of the power must flow out of the colineararm 102 corresponding to the original input arm. Thus,-by the use ofanother hybrid T the power contained in arms 53 and 58 of the hybrid Tcan be recombined and'the power of the original wave transmitted to theantenna.

The'use of the hybrid T-j-unction in the output of the rotary jointissubject to the same objection at the crossover position as whendirectional couplers. are used. The cross over position of the rotaryjoint using the hybrid T is shown in Figure 6 Wave 60 is applied throughthe 'input'guide 33 and upon reaching the opening 50 into waveguide 24divides into .three paths with one component 64 being directed by mitercorner 51 upward intO'H-armSS, another component 6-3 into Eearm .53 andthe thirdicoruponent around the circular guide 24 along path61 The wavetraveling path 61 on completing its path-around the 'circum ferenceofthe rotary joint splits in'to'the two components 65 and 66. Component 65is directed upward through opening 56 into H-arm 58 and combines withcomponent 64 to take path 67 out of the opening 54. Component 66 isdirected through opening 52 to combine with component 63, which thenpropa gates along path 62 in E arms S3 and out of the open+ ing' 55. Onthe recombination of the wave components in each respective arm, thewave components must travel "path-lengths of a wave length or multiplesof a wave length to avoid arriving in an out-ofphase relation with theconsequent reflection of energy'back toward the input." Although it ismore difiicult in actual practice to provide path lengths of multiplesof wave lengths when the hybrid T is used as the directive device, it ispossible to design a rotary joint using hybrid Tswith a minimum amountof out-of-phase recombination due to the wave path lengths. v

Referring now to Figures' 7 and 8, the basic rotary waveguide' joint-ofFigure 1 is converted into a switching structure by the addition ofanother directional coupler 70 into the wide face 22 of: circular guide24. D1- rectional coupler 70 is identical in all respects to directionalcouplers 35 and 42 and utilizes two mutually perpendicular couplingslots 71 and 72. A high dielectric-strength plug 73 is inserted in thecoupler wall opening' formed by the slots 71 and 72. Since the outputdirectional couplers are located on diametrically opposite sides bf'therotary joint, itcan be seen that each coupler willwt-ransferpower duringeach half revolution of the rotary joint. Thus, with the input waveguide33 located in the-position shown in Figure 8, the input wavepropagatesalong path 44 and is .directionally coupled by coupler '35into the circular waveguide 24 and along path 45. As the wave reachesthe coupling slots 39 and 40 in output directional coupler 42, the waveis directionally coupled along path 46. The directional coupler 42thuscouples the input wave to its antenna until the input coupler hasmoved relative to the output coupler 42 and is directly opposite.After'the cross-over point; has been reached, the wave propagating alongpath 45 will be coupled into directional coupler 70 by the slots 72 and73 and directional coupler 42 will receive no power until immediatelyafter the cross-over point of directional coupler 70 has been reached.Due to the properties of the directional coupler, it can be seen thatother couplers can be added to waveguide 24 to provide additional"outputs to antenna feeds. Insofar as the directional coupler tails tocouple 100 percent of the incident wave,': some: powefwill propagate;to. the :hominallylfoff arm: wThis extraneous-couplingican beeliminated. with a metallic plug 84 as will be discussedinthedescription ofthe hybrid T joint of Figure 10. It is also evidentthatthe mitered corner 51 of the plug 84 may be used to provide wave:directivity and eliminate directional coupler 35 of Figure 7.

In Figures 9 and 10, the structure of- Figure 4 is modilied to provide aswitching structure utilizing two hybrid Ts. In like manner to thedirectional couplers of Fig.- ure 7, the hybrid Ts are locateddiametrically opposite from each other on the circular waveguide 24 witharm representing the H-arm and arm 81 of the E-arm of the second outputhybrid'T- The path direction control of the rotary joint used as aswitching structure differs somewhat from the structure used with :asingle output! The cross-section view of Figure 10 illustrates theinternal construction of the switching structure and shows in additionto the miter corner .51 a solid plug 84 backing up the miter corner andextending through an arc length of 180 degrees. The back-up plug 84terminates in a plug '85 composed of a highly attenuative *lossymaterialz' Figure 10 also shows the -iris8'3 located in E-arm 81 tocancel any reflections from the junction. Plug 84 may be omitted ifiminor coupling to the nonener-gized-arm can be allowed,- however,miteredcorner 51 will still be required to :.d'irect the wave along path86.

With the input arm 33 located as shown in Figure '10, the wave path 60propagating through the input guide 33 isdirected by the miter cornerand back-up plugalon'g V the path -86-until it reaches the opening 82.into E-arm 81 Since the characteristic of hybrid Ts is that a wavepropagated into one colinear' arm does not enter the other colinear armbut divides between-the side arms, the wave following path 86 will bedirected-along path 87 into E-iarm 81 and upward into arm 80 not shownin this view. Should any waves propagate past the openings into the E.and H-arms of the hybrid T, .the lossy plug will absorb such energy andavoid reflections. When input arm 33 has rotated until the miter corner51 has reached the cross-over point of thehybr-id T containingE-arm 53,the input into opposite output hybrid T will beclosed from the inputwave by means of the plug '84. Thus, the input wave will be transmittedto the E and H-arms, 53 and '58 respectively, until input farm 3-3 hasrotated relatively a sufiicient amount to uncover the second outputhybrid T and close the first output hybrid T to the input waves. Shouldit be desired to add additional outputs, the arc length of the-back-upplug will be increased until only the arc length path between outputsremains uncovered. Thus, if three output hybrids are used, the

back-up plug '84 would extend .an arc length of 240 .de-'

grees and if four output hybrids were used, the back-up .plug 84 wouldextend for 270- degrees around the-circumferenceof the circle, 1 iAlthough this invention relates-to-a rotary joint suitable for 360degrees rotation with the necessary wave path directivity, there aremany instances in which movement through only a segment of a circle isrequired. It is evident that the rotary joint described above can bemodified to provide wave path directivity for those applicationsrequiring relative movement between the input and output guides throughany numberof degrees less than 360 degrees since it is also suitable:forcomplete rotation.

.Although the present invention has been-described with referencetospecific embodiments for botharotary joint and a switching structure,nevertheless, various modifica tions obvious to one skilled in the artthat would satisfactorilyserve the teachings :of this invention 'arewithin the spirit, scope, and Icontemplationofthe present in vention.

'What-is claimed is:

1. A rotary :wave'guideljoiritof the type wherein high freqfuencyienergyisccdpled from .atileast'oneinput waves l7 I guide to at least one otherrelatively rotatable output waveguide, said joint comprising a firstannular wall member, a second'annul ar wall member which is rotatablewithrespect to the first annular wall member andiwhich isplacedcoaxially. with and in close concentric proximity to saidfirstannular wall member to form a substantially enclosed annular waveguidecavity, means adapted to direct energy from said input waveguide intosaid annular waveguide, at least one opening in said annular waveguide,and means adapted to direct energy from said annular waveguide into saidoutput waveguide, said directing means being characterized by astructural arrangement lying wholly outside said annular Waveguide andcommunicating with said at least one opening.

2. A rotary Waveguide joint of the type wherein high frequency energy iscoupled from at least one input Wave guide to at least one otherrelatively rotatable output waveguide, said joint comprising a firstannular wall member, a second annular wall member which is rotatablewith respect to the first annular wall member and which is placedcoaxially with and in close concentric proximity to said first annularwall member to form a substantially enclosed annular waveguide cavity, adirectional coupler arranged to receive high frequency energy from saidinput waveguide andhaving' a wall in-common with said am nularwaveguide' and two mutually perpendicularslots formed in said commonwall with each slot resonant at the intended operating frequency of thejoint whereby substantially complete transfer of energy can be effectedfrom said coupler into said annular waveguide, and means adapted todirect energy from said annular waveguide into said output waveguide. 532: A joint as defined'in claim 2 wherein saidmeans adapted todirect-energy from said annular Waveguide includes a directional coupleradapted to pass energy into said output waveguide and having a wall incommon with said annular waveguide and two mutually perpendicular slotsformed in said common wall with each resonant at the intended operatingfrequency of the joint whereby substantially' complete transfer ofenergy can be effected from said annular waveguide into said coupler.

4. A joint as defined in claim 3 wherein a high di- 7 electric strengthplug is fitted intovsaid mutually perpendicular slots.

5. A joint as defined in claim 2. wherein a high dielectric strengthplug is fitted into said mutually. perpendicular slots.

6. A rotary waveguide joint of the type wherein high frequency energy iscoupled from at least one input waveguide to at least one otherrelatively'rot'atable output waveguide, said joint comprising a firstannular wall member,a second annular wall member which is rotatable withrespect to the first annular wall member and which is placed coaxiallywith and in close concentric proximity to said first annular wall memberto form a substantially enclosed annular waveguide cavity, a mitercorner associated with said input waveguide and extending into saidannularwaveguide adapted to direct energy from said input waveguide intosaid annular waveguide, openings in said wall members, and a hybrid Tformed with said annular waveguideand externally thereof, said hybrid Tbeing in communication with said openings and directing energy from saidannular waveguide into said at least one output waveguide.

7. A joint as defined in claim 6 wherein said hybrid T is constitutedbysaid annular waveguide functioning as-two colinear arms, an E-plane sidearm, and H-plane side arm, said sidearms being fed through openings insaid wall members. i

-8. A joint as definedin claim 7 wherein a matching element is:locatedin each of said side arms to produce reflections to cancel reflectionsfrom the T-junction.

9. A joint as defined in claim 6 wherein said hybrid connected to a'second hybrid T with correspgnding arms being connected together andsaid second hybridT is'adapted' to direct energy received from saidfirst-men tioned hybrid T into said output. waveguide.

10. A rotary waveguide switching structure wherein high frequency energyis coupled from at least one input waveguide to at least two otherrelatively rotatable output Waveguides comprising a first annular wallmember, a second annular wall member which is rotatable with respect tothe first annular wall member and which is placed coaxially with and inclose concentric proximity to said first wall member to form asubstantially enclosed annular Waveguide cavity, means adapted to directenergy from said input waveguide into said annular waveguide, openingsin said annular waveguide, and means adapted to direct energy from saidannular waveguide alternately into said output Waveguides, saiddirecting means being characterized by structural arrangements lyingwholly outside said annular waveguide and communicating withsaidopenings.

11. A rotary waveguide switching structure wherein high frequency energyisv coupled from at least one input waveguide to at least two otherrelatively rotatable output waveguides comprising a first annular wallmember, a second annular wall member which is rotatable with respect tothe first annular wall member and which is placed coaxially with and inclose concentric proximity to said first wall member to form asubstantially enclosed annular waveguide cavity, means adapted to directenergy from said input waveguide into said annular waveguide, and adirectional coupler associated with each said out: put waveguide andhaving a wall in common with said annular waveguide and two mutuallyperpendicular slots formedin said common wall with each slot resonant atthe design operating frequency of the structure whereby substantiallycomplete transfer of energy can be effected from said annular waveguideinto each said output waveguide, said directional couplers beingsymmetrically are ranged about said annular waveguide. 7 a 12. A rotarywaveguide switching structure wherein high frequency energy is coupledfrom at least one input Waveguide to at least two other relativelyrotatable output waveguides comprising a first annular wall member, asecond annular wall member which is rotatable with respect to the firstannular wall member and which is placed coaxially with and in closeconcentric proximity to said first Wall member to forma substantiallyenclosed annular waveguide cavity,-means adapted to direct energy fromsaid input waveguide into said annular waveguide, openings in saidannular waveguide, and at least two hybrid Ts formed with said annularwaveguide and externally thereof 'in communication with said openings,said hybrid Ts being symmetrically disposed about said annular waveguideand each adapted to transfer energy from said annular waveguide into itsassociated output Waveguide. e l3. A'structureas defined in claim 11wherein a high dielectric strength plug is fitted into each set ofmutually perpendicular slots. 914. A rotary waveguide switchingvstructure wherein high frequency energy is coupled from at least oneinput waveguide to at least two otherrelatively rotatable outputwaveguides comprising a first annular wall member, a second annular Wallmember which is rotatable with respect to the first annular wall memberand which is placed coaxially with and in close concentric proximity tosaid first wall member to form a substantially enclosed annularwaveguide cavity, means adapted to direct energy from said inputwaveguide into said annular waveguide, energy path controlling meansincluding a plug blocking said annular waveguide through an arc lengthin degrees equal to r where n is the number-of output waveguides,openings m'sa-idannular waveguide, and means symmetricailyarrangedaround said annular waveguide with eachin communication with at leastone of said openings and associated with one of said output waveguides,each said means being adapted to direct energy into its associatedwaveguide from said annular waveguide.

15. A structure as defined in claim 14 wherein said plug terminates witha portion composed of a highly attenuative lossy material.

16. An antenna coupling system wherein high frequency energy is coupledfrom at least one waveguide to at least one other relatively rotatablewaveguide which is to be connected to a rotatable antenna comprising thecombination of a first annular wall member, a second annular wall memberwhich is rotatable with respect to said first annular wall member andwhich is placed coaxially with and in close concentric proximity to saidfirst wall member to form a substantially enclosed annular waveguidecavity, a directional coupler arranged to receive high frequency energyfrom said input waveguide and having a wall in common with said annularwaveguide and two mutually perpendicular slots formed in said commonwall with each slot resonant at the intended operating frequency of thejoint whereby substantially complete transfer of energy can be elfectedfrom said coupler into said annular waveguide, means adapted to directenergy from said annular waveguide into said output waveguide, arotatable antenna, means connecting said rotatable waveguide to saidantenna, and means for continuously rotating said antenna, rotatablewaveguide, and rotatable wall member together as a unit.

17. An antenna coupling system wherein high frequency energy is coupledfrom at least one waveguide to at least one other relatively rotatablewaveguide which is to be connected to a rotatable antenna comprising thecombination of a first annular wall member, a second annular wall memberwhich is rotatable with respEct to said first annular wall member andwhich is placed coaxially with and in close concentric proximity to saidfirst wall member to form a substantially enclosed annular Waveguidecavity, a miter corner associated with said input Waveguide andextending into said annular waveguide adapted to direct energy from saidinput waveguide into said annular waveguide, a hybrid T adapted todirect energy from said annular waveguide into said output waveguide, arotatable antenna, means connecting said rotatable waveguide to saidantenna, and means for continuously rotating said antenna, rotatablewaveguide, and rotatable wall member together as a unit.

References Cited in the file of this patent

